RSTS/E

RSTS/E can be used for interactive timesharing, batch
processing, indirect command file processing, program
development using a variety of languages and tools, and a wide
variety of special purpose applications. Up to 127 concurrent
terminal users in both local and remote locations through
multi-terminal services can interact with application tasks.
Without multi-terminal services, 63 users are the maximum.
Tasks can share computational, storage, and input/output
services provided by the RSTS/E system.